Excerpted from https://news.ycombinator.com/item?id=10356933,
& lightly reformatted for this medium:

deckard1>   I used to be on the fence:  I knew I hated journald with a
            passion.  But for systemd, the last straw was trying to mount 
            a USB drive one day.  I would do "mount", and nothing was mounted. 
            I looked through the logs, and noticed it was being unmounted 
            on mount.  What the fuck, right?  Turns out, a prior unmount of 
            a USB stick killed some service that systemd runs.  So systemd 
            thinks the service is dead, which means it should not be mounted, 
            which means it keeps umounting the damn thing.  Totally braindead.

            That's also when I learned systemd was running an entire virtual 
            fstab layer.  Because, you know, /etc/fstab just isn't good enough 
            anymore.

sandGorgon> This is actually a good thing.  You might have found it
            bothersome, but what it was doing was intelligently trying 
            to reason whether a device would cause problems in your machine. 
            It did not make the correct decision, but the infrastructure 
            is there.  I would file a bug on systemd mentioning this behavior,
            but I like the fact that that my USB WiFi card will not screw 
            my system.

weland>     What was intelligent about that?  I don't need intelligent tools, 
            I need tools that do what I say!  That's why they're tools, damn it!